Yvette Argueta and her daughter were in their kitchen in Cudahy when the screams began.
Shrill cries pierced the night about 8 p.m. Monday, Argueta said, "like something horrible happened."
She heard a woman yell something about "a lot of blood" then a string of expletives.
Argueta said the screams were followed by the horrifying scene she saw from outside her home: two panicked parents running down their long driveway with their 3-year-old son's face and throat covered in blood.
The father said the little boy had stabbed himself in the face, she said. Argueta was terrified.
"I just hope the little boy is OK," she said late Tuesday morning.
Hours after paramedics arrived and whisked the toddler away to a hospital, Los Angeles County Sheriff's Department homicide detectives took the boy's mother, Michelle Betancourt, 23, into custody on suspicion of attempted murder. She's being held on $1 million bail.
Despite the parents' version of events, homicide Lt. Holly Francisco said the evidence does not suggest an accidental stabbing.
And the boy is not expected to survive.
According to neighbors, the screaming and profanity that spilled into the driveway from the home was nothing new in an otherwise quiet neighborhood.
Betancourt and her boyfriend regularly yelled at each other -- in front of the neighbors and in front of the kids, said a neighbor, who wouldn't give his name for fear of retaliation.
Normally, the neighbor would ignore the noise. But when he saw the injured, bloody child he called an ambulance.
"She was screaming, 'It was an accident. I was cutting lemons,'" the neighbor said, referring to Betancourt as he stood under a lemon tree in his front yard.
Just a couple feet from where the neighbor spoke lay the powder blue gloves the medics used to the treat the toddler.
He said Betancourt told him the toddler got a hold of the knife she was using and stabbed himself.
A second neighbor, the man said, took the toddler away from his mother and applied pressure to his wounds. There was blood on the child's neck and chest.
Officials said Tuesday it's not the first time neighbors have called authorities because of the couple. Sheriff's deputies have responded to domestic violence calls from both the boy's mother and father, Francisco said.
Over the course of the year that the family has lived on this residential street, neighbors have reported unrelenting fights.
"There's always screaming from him, screaming from her," said one neighbor.
Though Betancourt was booked for attempted murder, child abuse charges will likely be added and it could turn into a murder case if the boy dies, Francisco said.
Both parents are cooperating with investigators. The couple also has a 9-year-old daughter who was home at the time of the stabbing.